Hydrangeas are a popular garden plant in the UK and come in a variety of colours but you can change the colour by making additions to the soil07:58, 06 Jul 2026Hydrangeas are beloved garden plants across the UK, coming in numerous different shades. When properly maintained, they can produce blooms for months on end each year.‌According to one gardener, you can effortlessly help hydrangeas "bloom better" and alter their colour by adding a kitchen scrap to the soil. Taking to TikTok to reveal her gardening trick, Brittany, who uses the username allegedlybrittany, posted a video of her hydrangeas to her 28,000 followers.‌In the revealing clip, the gardener displayed her flowers: some had received kitchen scraps, while others had not, and the results were remarkable.‌The caption of the video said: "This is the difference between using coffee grounds and not. The deepest blue I've ever seen."Initially, the TikTok gardener presented the hydrangeas which hadn't received coffee grounds. While they were an attractive colour, they were lacking in blooms and appeared small, reports the Express.The video then moved across to the opposite side, where the hydrangeas had been treated with coffee grounds. They were a stunning shade of blue, with some appearing lighter in tone and others deeper.‌Content cannot be displayed without consentThey were also considerably larger, with numerous blooms throughout her front garden. Coffee grounds help transform hydrangeas blue by raising soil acidity, which enables the plant to absorb aluminium.When soil is acidic and low in pH, the flowers can readily absorb aluminium from the soil, triggering the chemical reaction that turns the petals blue. It's crucial to understand that this trick only works on certain varieties, such as lacecap, bigleaf and mophead.‌Varieties like oakleaf or smooth hydrangeas, such as Annabelle, will never turn blue.The clip, which garnered more than 145,000 likes, prompted an enthusiastic response from fellow gardening enthusiasts, who were taken aback by the results.Article continues belowUser Strawberri95 said: "I've not heard of this. How does it work? Do you sprinkle the grounds on the soil at the bottom of the plant? Or mix it with the soil?"Beth Dunn replied: "Sprinkle and water would work. You can also pour old coffee on the roots. The acidity changes the bloom colour and makes them bloom better."Alice Benson commented: "It adjusts the level of the soil's pH. Acidic soil promotes blue or lavender blue blooms, while alkaline soil encourages pink or red."